They haven't really been caught on anything. These aren't ad measurement results saying they did reach more people than exist, this is a reach estimation servic

They haven't really been caught on anything. These aren't ad measurement results saying they did reach more people than exist, this is a reach estimation service. It's a technically complex problem that needs to take an arbitrary targeting spec with boat loads of dimensionality and return a reach estimate in 100s of milliseconds. It's based on a sampling method, of course. The reach estimation tool is a planning tool for approximations and nothing more. That's why advertisers aren't making a big fuss.